Professor Yang Lu of the Department of Mechanical Engineering in collaboration with his research team and partners, conducted the research “Flexural phonon instability defines intrinsic van der Waals elastic limits in the interlayer direction”. The research findings were published in Nature Communications on June 10, 2026. 

Details of the publication:

Flexural phonon instability defines intrinsic van der Waals elastic limits in the interlayer direction

Heyi Wang, Miaojie Liu, Jiayi Li, Shizhe Feng, Yuan Hou, Man Kit Cheng, Ke Cao, Fanling Meng, Juzheng Chen, Zhiping Xu & Yang Lu

Article in Nature Communications

https://www.nature.com/articles/s41467-026-74353-w 

Abstract:

Frenkel’s cohesive model predicts an ideal elastic strain limit of ~10% for strong solids, a bound upheld in conventional materials. We demonstrate that such consistency breaks down in van der Waals (vdW) solids, challenging established strength theories. In situ tensile tests, combined with first-principles calculations, reveal unexpected localized decohesion failure at only ~3% strain in graphite and ~2% in h-BN along the interlayer direction—well below defect-controlled limits—defining their intrinsic elastic limits. This localization phenomenon is absent in MoS2, GaSe, and 3D crystals. We identify flexural phonon instability as the trigger for a cascade of strain localization, creating periodic nanogaps to release elastic strain energy. This dynamic instability redefines the intrinsic elastic limits of vdW crystals and opens pathways to tailor their structural/transport properties via strain engineering.